1. Field of the Invention
The present invention relates to a sanitary (hygienic) tampon to be inserted into a vagina for absorbing the menstrual blood.
2. Description of the Related Art
In recent years, a variety of products have been developed as the sanitary tampon. In Japanese Patent Laid-Open No. 146548/1989, for example, there is disclosed a sanitary tampon which is constructed to include an absorber made of hydrophilic fibers and an outer layer made of a hydrophobic sheet having hydrophilic fibers mixed therein. In Japanese Patent Laid-Open No. 146058/1991, on the other hand, there is disclosed a tampon which is constructed to include a column-shaped highly compressed core and an outer wall. In Japanese Patent Laid-Open No. 68695/1993, moreover, there is disclosed a tampon in which a sheet of a high fiber density and a sheet of a low fiber density are combined so that the sheet of a low fiber, density may partially appear in the surface when the tampon is formed into a column shape. In these tampons, the absorbent fiber material is compressed and formed into the column shape, and this compression is released by absorbing the menstrual blood when the tampon is used. As a result, the tampon swells to close the vaginal opening and absorbs the menstrual blood which is then continuously discharged.
However, the menstrual blood is so highly viscous that it hardly migrates into the central portion of the tampon of the related art but resides on the surface of the tampon. This lowers the absorption rate of the menstrual blood so that the compressed tampon takes a long time to restore its bulk. When much menstrual blood is discharged, on the other hand, it cannot be fully absorbed by the tampon, or the vaginal opening is not fully closed due to the low swelling rate of the tampon. As a result, the menstrual blood may leak. In the tampon of the related art, on the other hand, the menstrual blood hardly migrates into the central portion of the tampon so that the absorber in the central portion is not effectively exploited. Since the menstrual blood resides on the surface of the tampon, moreover, the tampon, when extracted after use, may present such a poor appearance as to make the user feel uncomfortable.